Wear detector



March 29, 1966 w. e. A. TROLLOPE 3,242,719

WEAR DETECTOR Filed June 2, 1964 2 Sheets-Sheet 1 28 PRESSURE SWITCH F/G.

|2 9 M SUPPLY {5% 5 l4 l2 38 PRESSURE SWITCH TO PRESSURE SWITCH 28 TO PRESSURE SWITCH 38 1 MI! I H 'Hl INVENTOR.

WILL/AM 6.14. TROLL OPE March 1966 w. G. A. TROLLOPE 3,242,719

WEAR DETECTOR Filed June 2, 1964 2 Sheets-Sheet 2 INVENTOR. WILL/A M 6. A. TROLL OPE United States Patent 3,242,719 WEAR DETECTOR William G. A. Trollope, Ville La Salle, Quebec, Canada,

assiguor to Canadian Ingersoll-Rand Co., Ltd, Montreal, Quebec, Canada, a corporation of Canada Filed June 2, 1964, Ser. No. 372,002 6 Claims. (Cl. 73--37.6)

This invention relates to detectors and more particularly to an improved wear detector. This is an improvement over my copending application entitled Wear Detector, Serial No. 357,611, which was filed April 6, 1964.

Heretofore, it is known that in a friction hoist, power is transmitted from the hoist wheel to the ropes by friction only. The hoisting rope or ropes run in grooves cut in special tread material fastened to the hoist drum. Such tread material is chosen for its high coefficient of friction, durability, etc. when working in conjunction with the ropes. Some friction materials which have been used for tread material are wood, leather, and polyurethane. Slippage between rope and tread does not take place in the course of normal operation, however the possibility of slippage is always present as for example a conveyance may jam in the shaft guides or the ropes may get wet.

Inasmuch as rope slip is accompanied by rapid tread wear, electrical devices have been heretofore employed to detect tread wear directly. These devices usually employ a number of wires embedded in the tread block with the outermost wire being connected through slip rings, in series with a relay. When slip occurs, the outermost wire is broken by the rope cutting through the tread. The break in the outermost wire de-energizes the relay and shuts down the hoist. This device, however, is difiicult and expensive to fit to an existing hoist because it requires the provision of slip rings and a special tread block fitted with embedded wire-s. In addition when a wire breaks it is a cumbersome task to connect the next wire in line in the circuit.

It is the general object of the present invention to avoid and overcome the foregoing and other difficulties of and objections to prior art practices by the provisions of a simple, reliable and relatively inexpensive wear detector.

Another object of the present invention is to provide a wear detector that can be installed easily.

Still another object of the present invention is to provide a wear detector that is easily adjustable thus being adaptable for a various number of uses.

The aforesaid objects of the present invention, and other objects which will become apparent as the description proceeds, are achieved by providing in combination means for establishing a pressure differential that varies as a surface wears and means actuated by said pressure differential for terminating said surface wear.

For a better understanding of the present invention reference should be had to the acompanying drawings, wherein like numerals of reference indicate similar parts throughout the several views and wherein:

FIG. 1 is a schematic view diagrammatically illustrating the wear detector of the present invention;

FIG. 2 is a vertical view of the wear detector;

FIG. 3 is a vertical view illustrating the wear detector fixed in position.

Although the principles of the present invention are broadly applicable to any type of wear detector apparatus, the present invention is particularly adapted for use in conjunction with the detection of the wear of a hoist tread block and hence it has been so illustrated and will be so described.

With specific reference to the form of the present invention illustrated in the drawings, and referring particularly to FIGS. 1, 2 and 3, a tread wear detector as- 3,242,719 Patented Mar. 29, 1966 sembly is indicated generally by the reference numeral 10. A stream of compressed air from a source of supply such as a hoist brake supply (not shown) or a mine supply (not shown) or some other source is supplied. to the tread wear detector 10 through a pipe 12. A reducing valve 14 disposed on the pipe 12 serves to reduce the air stream pressure to some constant value suitable to the particular conditions of the situation. A pressure between 3 to 10 p.s.i.g. has been found suitable for most uses.

In order to establish a pressure differential in the tread wear detector 10, pressure differential means such as a restriction 16, disposed on the pipe 12 on the down stream side of the reducing valve 14, and a nozzle 18 disposed at the tread end 20 of the pipe 12 adjacent the groove 22 of the tread block 24 of a hoist 26 are provided. As illustrated in FIG. 1, the groove 22 is of concave configuration and the nozzle 18 extends within the concavity of the groove 22 to discharge compressed air upon the bottom surface thereof from a position within the concavity of the groove 22. It will be understood that the restriction 16 and the action of the air stream jetted from the nozzle 18 acting against the surface of the groove 22 will produce a pressure differential in the pipe 12 between the restriction 16 and the nozzle 18. The restriction 16 can be made variable by means of a set screw 19 so that the tread wear detector 10 can accommodate various uses.

It will further be understood that the pressure differ ential in the pipe 12 will drop when the distance from the nozzle 18 to the groove 22 is increased from the wear of the tread block 24 which Wear is, of course, caused by slippage between the rope (not shown) and the tread block 24 of the hoist 26.

In order to stop the hoist 26 when slippage occurs a shut off means, such as a pressure switch 28, is piped into the pipe 12 between the restriction 16 and the nozzle 1.8-. The pressure switch 28 is connected to the hoist safety circuit and is set to react to a pressure drop in the pipe 12 to cut off power to the hoist 26 to stop the hoist 26.

It will thus be understood that if slippage occurs and the tread block wears, the increased distance between the nozzle and the groove 22 will cause the pressure to drop in the pipe 12. This pressure drop, as will be seen, will immediately activate the pressure switch 28 to stop the hoist 26. Thus the hoist 26 will stop immediately upon the occurrence of slippage.

It has been found that sometimes dirt collects around the nozzle 18, between the nozzle 18 and the groove 22, and causes a restriction on the nozzle opening. The restriction in the nozzle opening will raise the pressure in pipe 12. With higher pressure in the pipe 12 the pressure switch 28 will not be activated as promptly as required and under certain conditions may not even work at all.

In order for the wear detector to detect a rise as well as a drop of pressure in the pipe 12, a second shut off means such as a second pressure switch 38 is piped into the pipe 12 between the restriction 16 and the nozzle 18. The second pressure switch 38 is connected to the hoist safety circuit (not shown) in series with the first pressure switch 28 and is set to react to a pressure rise in the pipe 12 to cut off power to the hoist 26 .to stop the hoist 26.

It will thus be understood that the tread wear detector 10 will react to either a pressure drop or a pressure rise in the pipe 12 to stop the hoist 26.

As shown in FIG. 2, the tread wear detector 10, is provided with a simple frame 30 that can be made of plate material such as steel or aluminum. The frame 30 can be easily fixed to a base 32 adjacent the hoist 26 by any number of well-known methods such as by bolting. It has been found that for best results in most uses the bottom of the tread groove 22 should be less than d/4 from the nozzle 18, where d is the diameter of the flow opening in the nozzle 18. The nozzle 18 may be conveniently provided with some form of adjusting means, such as for example a screw adjustment (not shown) for re-positioning the nozzle 18 closer to the groove 22 as the tread block 24 wears.

It will be recognized by those skilled in the art that the objects of the present invention have been achieved by providing a simple tread wear detector that is reliable and easily installed.

While in accordance with the patent statutes a preferred embodiment of the present invention has been illustrated and described in detail, it is to be particularly understood that the invention is not limited thereto or thereby.

I claim:

1. An apparatus for detecting wear of a groove located circum ferentially around a rotating member and for stopping rotation of said rotating member in response to Wear of said groove, said apparatus comprising:

a source of pressurized air;

a conduit operatively connected to said source of pressurized air to receive presurized air therefrom and extending adjacent said groove;

a stationary nozzle upon said conduit adjacent said groove for directing pressurized air from said conduit against a surface of said groove from a constant position adjacent said groove;

a valve interposed within said conduit intermediate said source of pressurized air and said nozzle for causing pressurized air at a constant pressure to How through said conduit towards said nozzle;

a first pressure actuated mean interposed within said conduit intermediate said valve and said nozzle, said first pressure actuated means being responsive to a drop in the pressure of the pressurized air flowing through said conduit intermediate said valve and said nozzle to stop rotation of said rotating member; and

a second pressure actuated means interposed within said conduit intermediate said valve and said nozzle, said second pressure actuated means being responsive to a rise in the pressure of the pressurized air flowing through said conduit intermediate said valve and said nozzle to stop rotation of said rotating member.

2. An apparatus for detecting wear of a groove located circumferentially around a rotating member and for stopping rotation of said rotating member in response to wear of said groove, said apparatus comprising:

a source of pressurized air;

a conduit operatively connected to said source of pressurized air to receive pressurized air therefrom and extending adjacent said groove;

a stationary nozzle upon said conduit adjacent said groove and extending within said groove for directing pressurized air from said conduit against a surface of said groove from a constant position within said groove;

a valve interposed within said conduit intermediate said source of pressurized air and said nozzle for causing pressurized air at a constant pressure to flow through said conduit towards said nozzle;

a first pressure actuated switch operatively connected to said rotating member to stop the rotation thereof, said first pressure actuated switch being interposed in said conduit intermediate said valve and said nozzle to be actuated by a drop in the pressure of the pressurized fluid in said conduit intermediate said valve and said nozzle to stop the rotation of said rotating member; and

a second pressure actuated switch operatively connected to said rotating member to stop the rotation thereof, said second pressure actuated switch being interposed in said conduit intermediate said valve and said nozzle to be actuated by a rise in the pressure of the pressurized fluid in said conduit intermediate said valve and said nozzle to stop the rotation of said rotating member.

3. An apparatus for detecting wear of a rope tread groove in a rotating hoist drum and for stopping rotation of said hoist drum in response .to the wear of said groove, said apparatus comprising:

a source of pressurized air;

a conduit operatively connected to said source of pressurized air to receive pressurized air therefrom and extending adjacent said rope tread groove;

a stationary nozzle upon said conduit adjacent said rope tread groove and extending within said rope tread groove to direct pressurized air upon the bottom surface thereof from a constant position within said rope tread groove;

a valve interposed within said conduit intermediate said source of pressurized air and said nozzle for causing pressurized air at a constant presure to flow through said conduit towards said nozzle;

a first pressure actuated switch interposed within said conduit intermediate said valve and said nozzle to be actuated by a drop in the pressure of the pressurized air within said conduit intermediate said valve and said nozzle, said first pressure actuated switch being operatively connected to said hoist drum to stop rotation thereof upon a drop in the pressure of said pressurized air; and

a second pressure actuated switch interposed within said conduit intermediate said valve and said nozzle to be actuated by a rise in the pressure of the pressurized air within said conduit intermediate said valve and said nozzle, said second pressure actuated switch being operatively connected to said hoist drum to stop rotation thereof upon a rise of the pressure of said pressurized air.

4. A wear detecting apparatus according to claim 3, wherein the nozzle extends into the rope tread groove to direct pressurized air upon the bottom surface thereof from a distance that is of a ratio of less than 1 to 4 relative to the flow diameter of said nozzle.

5. A wear detecting apparatus according to claim 4, wherein the valve is adjustable to vary the constant pressure of the pressurized air flowing towards said nozzle.

6. A Wear detecting apparatus according to claim 4, wherein said rope tread groove is of concave configuration.

References Cited by the Examiner UNITED STATES PATENTS 2,718,140 9/1955 Aller 73-375 2,881,528 4/1959 Moore 7337.9 X 2,888,023 5/ 1959 Eggenberger.

LOUIS R. PRINCE, Primary Examiner.

F. H. THOMPSON, Assistant Examiner. 

1. AN APPARATUS FOR DETECTING WEAR OF A GROOVE LOCATED CIRCUMFERENTIALLY AROUND A ROTATING MEMBER AND FOR STOPPING ROTATION OF SAID ROTATING MEMBER IN RESPONSE TO WEAR OF SAID GROOVE, SAID APPARATUS COMPRISING: A SOURCE OF PRESSURIZED AIR, A CONDUIT OPERATIVELY CONNECTED TO SAID SOURCE OF PRESSURIZED AIR TO RECEIVE PRESSURIZED AIR THEREFROM AND EXTENDING ADJACENT SAID GROOVE; A STATIONARY NOZZLE UPON SAID CONDUIT ADJACENT SAID GROOVE FOR DIRECTING PRESSURIZED AIR FROM SAID CONGUIT AGAINST A SURFACE OF SAID GROOVE FROM A CONSTANT POSITION ADJACENT SAID GROOVE; A VALVE INTERPOSED WITHIN SAID CONDUIT INTERMEDIATE SAID SOURCE OF PRESSURIZED AIR AND SAID NOZZLE FOR CAUSING PRESSURIZED AIR AT A CONSTANT PRESSURE TO FLOW THROUGH SAID CONDUIT TOWARDS SAID NOZZLE; A FIRST PRESSURE ACTUATED MEAN INTERPOSED WITHIN SAID CONDUIT INTERMEDIATE SAID VALVE AND SAID NOZZLE, SAID FIRST PRESSURE ACTUATED MEANS BEING RESPONSIVE TO A DROP IN THE PRESSURE OF THE PRESSURIZED AIR FLOWING THROUGH SAID CONDUIT INTERMEDIATE SAID VALVE AND SAID NOZZLE TO STOP ROTATION OF SAID ROTATING MEMBER; AND A SECOND PRESSURE ACTUATED MEANS INTERPOSED WITHIN SAID CONDUIT INTERMEDIATE SAID VALVE AND SAID NOZZLE, SAID SECOND PRESSURE ACTUATED MEANS BEING RESPONSIVE TO A RISE IN THE PRESSURE OF THE PRESSURIZED AIR FLOWING THROUGH SAID CONDUIT INTERMEDIATE SAID VALVE AND SAID NOZZLE TO STOP ROTATION OF SAID ROTATING MEMBER. 